MANAGEMENT IN THE REPUBLIC OF SEYCHELLES THE STUDY FOR COASTAL EROSION AND FLOOD CONTROL MINISTRY OF ENVIRONMENT AND ENERGY REPUBLIC OF SEYCHELLES THE STUDY FOR COASTAL EROSION AND FLOOD CONTROL MANAGEMENT IN THE REPUBLIC OF SEYCHELLES FINAL REPORT FINAL REPORT MARCH 2014 MARCH 2014 JAPAN INTERNATIONAL COOPERATION AGENCY (JICA) CENTRAL CONSULTANT INC. CTI ENGINEERING INTERNATIONAL CO., LTD. GE JR 10-070 MANAGEMENT IN THE REPUBLIC OF SEYCHELLES THE STUDY FOR COASTAL EROSION AND FLOOD CONTROL MINISTRY OF ENVIRONMENT AND ENERGY REPUBLIC OF SEYCHELLES THE STUDY FOR COASTAL EROSION AND FLOOD CONTROL MANAGEMENT IN THE REPUBLIC OF SEYCHELLES FINAL REPORT FINAL REPORT MARCH 2014 MARCH 2014 JAPAN INTERNATIONAL COOPERATION AGENCY (JICA) CENTRAL CONSULTANT INC. CTI ENGINEERING INTERNATIONAL CO., LTD. GE JR 10-070 Exchange Rate US$ 1 = SCR 11.381 = JPY 102.19 February 2014 Summary Summary 1. Introduction The Republic of Seychelles consists of over 115 islands scattered in the Western Indian Ocean and has a total land area of 452 km2. The population was estimated at 87,000 in 2011 with over 90% concentrated in the narrow coastal strips around the three main islands of Mahe, Praslin and La Digue. The country depends on its coastal zone for most of its economic activities such as tourism and fishing. About 200,000 tourists visit the Seychelles annually. The coastal zone has been affected by several disasters in recent years, such as the coastal erosion of Anse Kerlan on Praslin since 1986, disasters caused by the Indian Ocean Tsunami in 2004, three days of inundation in Victoria in 2004, and flooding in the southeast of Mahe in January 2013. Because of the sea level rise and increased rainfall intensity caused by climate change, the risk of natural disasters is increasing, alongside anthropogenic influence such as tourism and housing development in the coastal zone. The study was conducted to formulate a coastal conservation plan and flood management plan to mitigate coastal erosion and flooding in the coastal zone, implement pilot projects which are applicable to the conditions in the Seychelles and undertake the related technology transfer. 2. Present Condition of Coastal Erosion and Flooding The extent of coastal erosion was investigated from old maps, aerial photos and field investigations and classified into (1) coasts with long-term erosion, (2) coasts with seasonal changes by wave conditions, (3) coasts with erosion and accretion caused by the construction of structures, and (4) stable coasts. At North East Point and Baie Lazare the coast has been eroded presumably by offshore sediment transport caused by longshore transport or flooding though the reef channel. At North East Point and Beau Vallon in Mahe and Anse Kerlan in Praslin, the coast changes seasonally. If the coast has a wide beach which can accept the seasonal variations, there are no erosion problems. The groynes at Anse Kerlan and breakwaters at La Passe have caused erosion and accretion around the structures. Past flooding was investigated from the records of disasters, analysis of the hydraulic conditions and field investigations and classified into (1) improper drainage, (2) increased run-off caused by urbanisation, (3) development of lowland areas, and (4) river mouth problems. At Victoria drainage problems were caused in some areas by reclamation fronting the old town and urbanisation. The development of lowland areas such as the construction of schools, public facilities and housing has caused inundation problems because of the limited flat land in the Seychelles. The reclamation for the international airport has caused inundation problems. The development of the wetland at Anse Au Pins, Au Cap and Anse Royale in Mahe and in La Digue brings inundation of those areas. Drainage from lowland to the sea is also made difficult because of accumulation of sand at the mouth by waves. The main strategies related to coastal conservation and flood management in the Seychelles are the S S- 1- 1 Seychelles Sustainable Development Strategy (SSDS 2012-2020), National Climate Change Strategy (2009), and National Disaster Management Policy (2011). These strategies include an integrated coastal zone management plan and related action plans. Laws for the management of disasters include the Town and Country Act (1975), Town and Country Planning Act (1972), Environment Protection Act (1994), Beach Control Act (1971) and Removal of Sand and Gravel Act (1991). Environmental impact assessment (EIA) is also established by the regulations (1996). The main organisations for coastal disaster management are the Ministry of Environment and Energy, Ministry of Land Use and Housing and Ministry of Community Development, Social Affairs and Sports. In the Department of Environment of the Ministry of Environment and Energy, the Climate Affairs, Adaptation and Information Division, National Meteorological Services and Coastal Adaptation and Management Section deal with coastal zone management which includes coastal erosion and flooding problems. The Divisions of Risk and Disaster Management in the Department is responsible for disaster response and disaster risk management. The Ministry of Land Use and Housing has authority regarding land use planning and regulation. The main issues are: . Coastal erosion and flood damage in lowland areas are caused by the construction of roads, breakwaters, houses and schools without consideration for the natural characteristics. The system and organisation of coastal management and EIA do not function effectively because of the lack of manpower and experience. There have been few past disasters and public interest in disasters is scarce due to limited basic information. The existing disaster management plan does not fully address the characteristics and limitations of the Seychelles. New types of disaster are expected due to further national economic development and climate change in the future in the coastal zone. 3. Coastal Management Plan The coastal conservation plan and flood management plan were formulated based on the management cycle of (1) issue identification and baseline assessment, (2) management plan preparation and adoption, (3) action plan and project implementation and (4) monitoring and evaluation. Information management and education are also considered. The objectives of the management plan are: . To mitigate the damage to human lives and property from coastal erosion, flooding, tides, waves and tsunamis. To harmonise the mitigation measures with nature conservation and the use of coastal areas, wetlands and rivers. To contribute to coastal zone development and climate change adaptation for sustainable development in the future. To promote awareness and understanding of the value of the coasts and rivers and bring S S- 2- 2 together stakeholders. The target year and design return period for the plan were decided as shown in Table 1. Table 1: Target Year and Design Period Short Term Medium Term Long Term Target Year 2020 2050 2100 Design Return Period Area Small Scale Medium Scale Large Scale Victoria Town 10 years 25 years 100 years Others 5 years 25 years 100 years The coastal or flood risk areas were classified and the risks evaluated. The measures were investigated from several alternatives for protection, accommodation and retreat. Sand nourishment and groyne construction for coastal erosion and drainage improvement and river improvement for flood control were selected as structural measures. As accommodation, measures such as land use regulations, warnings, emergency operation, public awareness and EIA were selected. The implementation schedule is from short to medium term for structural measures and from short to long term for non-structural measures. The coastal conservation and flood management plans were formulated for the priority coasts or areas as action plans. The priority areas were selected based on necessity, urgency, technical characteristics and future development. The selected areas are North East Point and Baie Lazare in Mahe, Anse Kerlan in Praslin and La Passe in La Digue for coastal conservation and Victoria, Point Larue, Anse Au Pins, Au Cap and Anse Royale in Mahe for flood management. 4. Coastal Conservation Plan for Priority Coasts North East Point The 2km-long coast is located in the northeast part of Mahe and is protected by a narrow coral reef and beach rock. Waves come from the northwest from November to April and from the southeast from May to October. A coastal road and houses are located along the coast and the beach is used by local residents for recreation. The problems are erosion and wave run-up at high tide on the coastal road that affects traffic. The beach was eroded for 30m in width from 1960 to 2011 and the seasonal variation was about 20 m. The possible causes of the long-term erosion are offshore transport. The proposed measures are sand nourishment for 20m in width for a 2 km stretch of the beach with maintenance nourishment. Sand or gravel nourishment is selected to compensate for the loss of sand and to keep beach use even the needs of maintenance nourishment because revetments cause loss of sand in front of the revetment. Baie Lazare The coast is located on the southwest coast of Mahe and is partly protected by a coral reef. Wetland has formed behind the sand bar where a coastal road and houses are located. The Baie Lazare River flows into the wetland and flushes out the sand bar in times of flooding. This possibly causes the loss of sand from the beach. S S- 3- 3 The problems are coastal erosion and wave run-up that affects the coastal road, shops and houses along the beach. Coastal erosion started two or three years before 2008. Wave run-up and coral debris were reported during the high tide in May 2007. Stone and wooden pile revetments were constructed in the past and today broken revetments remain. The proposed measures are sand nourishment for 20m in width for a 400 m stretch of the beach with maintenance nourishment. It is necessary to monitor the beach profile to estimate the causes of erosion and the necessary sand volume for maintenance.